Calandria



H. M. HUNTER June 11, 1940.

CALANDRIA Filed March 28, 1938 Zinnentor HENRY M HUNTER I (Ittornegs Patented June 11, 1940 PATENT OFFICE CALANDRIA Henry M. Hunter, New York,,N.' Y., assignor to Goslin-Birmingham Manufacturing Company, 'Inc., a' corporation of Alabama Application March 28 1938, Serial No. 198,501

7 Claims.

This invention relates to evaporators and vacuum pans, and more particularly to the steam chest or calandria thereof, and has for its object the provision of improved means for effecting heat transfer in the calandria.

A more particular object of my invention is to provide, in apparatus of the character designated, an improved means for removing the noncondensable gases from the steam side ofthe calandria tubes.

A more specific object of my invention is to provide an improved system of baffles in the calandria whereby the steam employed for heating is more effectively distributed aroundthe calandria tubes and in which the non-condensable gases are removed in such a manner that there is a minimum of dead air, or'inactive space around the tubes.

As is known in the art to which my' invention relates, one of the most obstinate prob-' lems to be overcome in the design of 'eVaporators is the removal of non-condensable' gases from the steam side of the heating surfaces. These non-condensable gases, consisting offair originally dissolved in the water or drawn in through faulty seams or leaky connections,- organic acids which may be dissolved in the. juices being evaporated in a previous efiect, par-' ticularly carbon dioxide, some ammonia, and

perhaps others, are very detrimental to heat transfer.

pressure, but they accumulate in certain spots,

pockets or stratifications, andtend to cling to the surfaces of the tubes where they can do the most harm, beingdriven there by the constantflow of steam in this direction. Some of .these gases are corrosive in nature and tend to pit and:

Their thorn-- ough and prompt removal is therefore highly;

damage the tubes and tube sheets.

important.

In accordance with my invention I haveover-n come the difficulty heretofore ordinarily-en countered in the removal of non-co ndensable gases by the provision of an improved system,

of baffling in a calandria having'tangential steam inlets. I have found, in such a calandria, that if a steam belt open freely to the "tube nest be" provided around the calandria, and'bafllescurve d in the direction of steam flow be provided'in thetube sheet l4.

through the center of the calandria and is also They not only reduce the temperature of steam or vapor by exerting a partial-vapor (o1. 2572 24) lets and are removed directly. The tube nest,

being open directly to the steam belt, without any intervening plates, affords the maximum contact of steam with the tubes, with maximum velocity flow around the tubes, and unrestricted entry into the tube nest, thereby providing optimum conditions for heat-transfer.

Apparatus embodying features of my invention is illustrated in the accompanying drawing form having a body I0 comprising an upper vapor chamber where separation of liquidand vapor take place, and a calandria at the lower end of the evaporator body. The calandria comprises a tube nest l2, the tubes of which extend through an upper tube sheet [3 and a lower A down take well l5 extends joinedto the upper and lower tube sheets I3 and I4.' Surrounding'the tube nest I2 is a steam belt l6 formed as an annular passage in the side of the shell surrounding the tube nest,

there being no baflles or plates between the steam belt and the tube nest as have heretofore been provided. Diametrically, opposite tangential steam inlets I! and I8 are connected to the steam belt soas to cause the steam entering the calandria to flow around the steam belt and directly into the tube nest I2.

Connecting the steam belt l6 and the downtake I5 are a plurality of baflles [9, 2|, 22 and 23 which are joined to the upper and lower tube'sheets l3 and I4, and extend to the downtake well, as seen in Fig. l, and which cooperate to form a plurality of radial inwardly extending heating zones, each decreasing in area as it approaches the down-take well. l5. The baffles 19 to 23 inclusive, as shown in they drawing, are curved in the direction of steam flowv to catch and direct the stream of steam, and are spaced around the steam belt 16 whereby the steam is directed into the heating zones with a minimum of interference to its flow. While the, bafiles 19, 2|, 22 and 23 are described as curved, it will be seen that, due to the lay out of the tube nest, a true curve cannot be obtained. The term curved as used herein is therefore intended as describing the general shape of said baffles.

Located adjacent the juncture of each of the baflles l9, 2E, 22 and 723 and the down-take well l5, in the bottom tube sheet M, is a condensate outlet 24. Above the condensate outlet, in the upper tube sheet [3, is an outlet 26 for air and other non-condensable gases. A perforated tube 21 extends downwardly from the outlet 26 to a point near the lower tube sheet 14 and connects to an off-take tube 28 above the tube sheet I3, which tube 28 is connected to a pipe 29 which leads outside of the evaporator as is well understood. The condensate outlets 2d are connected to drains 25, which lead outside the evaporator and may connect to a common drainage pipe '30.

It will be apparent from the foregoing that when steam is admitted to the calandria ll through the tangential inlets l! and I8 into the steam belt I6 it is inclined, by its own momentum, to follow the steam belt l around the tube nest M. It is drawn into the tube nest by the heat transfer through the tubes and condensation, the curved baffles I9, 2!, L22 and 23 guiding the flow of the steam inwardly toward the down-take well l5, bringing about a maximum of contact with the tubes in the tube nest l2, and causing a concentration of the non-condensable gases in the restricted area of the juncture of the spiral baffles with the down-take well. The non-condensable gases now pass outwardly of the evaporator through the perforated tubes 2i and the off-take tubes 28 and 29. The condensate drains through the outlets 24 and the drain pipes 25 and 30. It will be apparent that this arrangement affords ideal heat transfer conditions, a maximum removal of non-condensable gases, and a minimum of dead space caused by non-condensable gases in the tube nest.

While I have shown my invention in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various changes and modifications, without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or as are specifically set forth in the appended claims.

What I claim is:

1. A calandria having a central down-take well, a tube nest, and a tangential steam inlet, means forming an annular steam belt surrounding the tube nest, a plurality of radially extending bafiles curved in the direction of entering steam flow connecting the steam belt and the down-take well, and off-take means for noncondensable gases located near the juncture of the spiral baffles and the down-take well.

2. A calandria having a central down-take well joined to the upper and lower tube sheets and a tube nest surrounding the well, a plurality of tangential steam inlets to the calendria, means forming an annular steam belt surrounding the tube nest and open freely to the tube nest, a plurality of radially extending baffles curved in the direction of entering steam flow and extending from the steam belt inwardly to join the down-take well, and outlet means for non-condensable gases and condensate in the tube sheets adjacent the juncture of the baflies with the down-take well.

3. A calandria comprising upper and lower tube sheets, a central down-take well joined to the upper and lower tube sheets, a tube nest surrounding the down-take well, radially extending curved baffles connected to the upper and lower tube sheets and extending inwardly of the tube nest to the down-take well forming between them separate radial heating zones of decreasing cross sectional area, a plurality of tangential steam inlets into the calandria, means defining a steam belt to which the inlets are connected and completely surrounding the tube nest, the

tube nest being freely open to the steam belt, and oif-take means for non-condensable gases and condensate in the tube sheets adjacent the juncture of the baffles and the down-take well.

4. In a calandria, a tube nest, a down-take well disposed centrally of the tube nest, an outer shell surrounding the tube nest, an annular steam passage formed in the outer shell, tangential steam inlets to the steam passage, bafile walls in the tube nest curved in the direction of entering steam flow and dividing it into separate converging heating zones, said walls extending radially inward to the down-take well, and off: take means for non-condensable gases and condensate disposed adjacent the juncture of the curved walls and the down-take well.

5. .A calandria comprising a shell enclosing a tube nest having a central down-take well, means in the shell forming an annular steam passage surrounding the tube nest and freely connected therewith, tangential steam inlets into the annular passage, a plurality of baffles curved in the direction of entering steam flow dividing the tube nest into a plurolity of converging heating zones and guiding the steam radially inwardly of the tube nest, and means adjacent the down-take well to remove condensate and noncondensate gases.

6. A calandria comprising a shell enclosing-a tube nest having a central down-take well, means in the shell forming an annular steam passage defined by the outer wall of the shell and the tube nest so as to be freely connected with the latter, tangential steam inlets into the annular passage, radially extending baffies curbed in the direction of entering steam fiow dividing the tube nest into a plurality of converging heating zones and guiding the steam inwardly of the tube nest, and means on the windward side of each of said baflles adjacent its juncture with the down-take well to remove condensate and noncondensable gases.

7. In a calandria, the combination with an outer shell having an annular steam passage formed therein, a tube nest enclosed by the shell and open to the steam passage and a central down-take well, of a plurality of curved baffles, each extending radially inward from the steam passage to divide the tube nest into a plurality of heating zones, said baifles leading inwardly of the tube nest to the down-take well and being curved in the direction of entering steam flow, oif-take means for non-condensable gases and condensate disposed in the areas formed the junctures of the baffles and the clown-take well, and tangential steam inlet means leading into the passage.

HENRY M. HUNTER. 

